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Remove Algae From the Roof

  • Transcript

    LESLIE: Free FM, WJFK is where Mike in Virginia listens to The Money Pit. And you’ve got some algae on your roof. Tell us about where it is on the roof; what side of the house it’s on.

    MIKE: Sure. It’s up on the section of the roof that’s covered – a portion of it’s covered by some trees that are overhanging.


    MIKE: So it’s a shaded area. And I was up there doing some repairs and I noticed that algae was growing up close to the peak of the roof.

    TOM: OK.

    MIKE: And just wanted to know what’s the best way to treat that.

    TOM: Well, first of all, understand that algae’s not going to hurt your roof. If it gets thick enough it can sometime push up shingles maybe sometimes and it potentially could cause a leak that way. But for the most part, it – not a problem.

    The way you get rid of it – well, I would recommend a product called Jomax – J-o-m-a-x – available at most home centers. You mix it up; you spray it down; you let it sit for a good 15 minutes. It will kill the algae. And then you can scrub it off and it won’t come back. For a longer term solution, you can actually change the type of flashing up there, right Leslie?

    LESLIE: Yeah, you can actually add a nickel ridge vent or a copper ridge vent. And what happens is, as it rains, the water interacts with the mineral makeup of the nickel or the copper and it causes this component to run down your roof and you’ll actually see it start to get rid of that moss, mildew, algae, whatever you want to call it; but it’ll do the work for you. And if you don’t feel like investing in the Jomax, you can also create a little mixture of your own mildicide of bleach and water; as long as you can scrub it. And try to do it on a day when there’s the most amount of sun getting to that area. And it should do the trick.

    MIKE: OK, great. Thank you very much.

    TOM: And Mike, one more thing. If you – you did mention that it was a shady area and that’s very, very typical. So the other thing that you could look to do is cut back some of those overhanging trees; enough to just, perhaps, to let a little more light in there and that will make it a lot less likely it’ll grow back.

    MIKE: Absolutely. That’s a great idea. Thank you.

    TOM: You’re welcome, Mike. Thanks so much for calling us at 888-MONEY-PIT.

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